Did you solicit this or is it a friend etc.? Basically, how did you get this offer? If you don't know and/or didn't try to get this job, I'd say it sounds fishy. If you understand how this offer came to be, just send an email back in proper business letter format and tell them you would be glad to do the work.

Tell them you're interested and that you'd like more info on the shoots. Also ask them if you'd be able to retain a license to use the images for your personal portfolio and advertising your photography [business].